Support is sought for a series of projects designed to increase our understanding of the effects of craniofacial birth defects on the process of speech production. The first group of studies consists of a phased series of aerodynamic investigations utilizing the equipment configuration and principles developed by Warren and associates. These studies have been designed (1) to provide information necessary for the development of standardized test protocols through expansion of modeling data, and (2) to investigate application of these protocols to the study of a) variability in velopharyngeal orifice area calculations in speakers with velopharyngeal incompetence, b) the effect of varying degrees of oral-nasal coupling in the production of stop consonants, c) the nasorespiratory function of speakers with the syndromes of Apert and Crouzon, and d) the initial and long-term effects of pharyngeal flap on nasorespiratory function. The second group of studies continues our previous work on the acoustical and perceptual parameters of speech produced by patients with aberrant supralaryngeal vocal tracts. The projects include development and application of computer-implemented vocal tract models to study the acoustic consequences of the agnormal vocal tract in the syndromes of Apert and Crouzon. Both groups of studies represent extension of a specific investigative technique beyond the purpose for which that technique was originally designed. While a number of studies have investigated pressure/flow patterns in patients with cleft palate, only two studies to date have reported aerodynamic data in speakers with other congenital craniofacial defects. The inauguration of such studies within the Center for Craniofacial Anomalies, with a patient population unsurpassed in size and diversity, thus constitutes a significant expansion in the application of this investigative approach. Similarly, vocal tract modeling utilizing computerized analysis and synthesis of the acoustic signal has been used previously only with the normal vocal tract. We propose to establish the efficacy of adapting this approach to studying the configuration and output of the abnormal vocal tract, with the ultimate goals of studying a variety of syndromes and perhaps providing information on what changes in the vocal tract configuration would allow the speaker to approach normal area function.